According to the Daily Star, producers believe Flack has the right credentials to present the spin-off show.
Her past TV work includes fronting The Pepsi Chart Show and Saturday morning children's programme TMi.
She also appeared on Big Brother's Big Mouth as a guest earlier this year.
"Caroline is sexy and sassy," said a source. "She has got all the quirky qualities you need to not only deal with the housemates but also their freaky friends and family."
Dermot O'Leary quit the show earlier this year to focus on his work with ITV's X Factor.
Big Brother 9 will be hosted by its regular presenter Davina McCall when it begins in May.